Conventional concrete is a mixture of cement, sand, aggregate, and water. The addition of materials to cement to lower the weight of the concrete, to increase insulating qualities, and to impart other desirable properties is well known in the art. Adding sawdust or other low-density materials to reduce the weight of the composition and to improve insulating properties is illustrated in U.S. Pat. No. 889,569 to Albrecht (1908), U.S. Pat. No. 1,039,038 to Light (1919), U.S. Pat. No. 1,463,123 to McAllister (1922), U.S. Pat. No. 1,384,370 to Bartlett (1924), U.S. Pat. No. 2,057,330 to Eichert (1936), U.S. Pat. No. 2,592,345 to Schnell and Bosshard (1947), U.S. Pat. No. 2,899,325 to Kranz et al. (1952), U.S. Pat. No. 3,264,125 to Bourlin (1966), U.S. Pat. No. 4,166,455 to Araujo and Tick (1977) and U.S. Pat. No. 5,207,830 to Cowan et al. (1993). In addition to sawdust, other organic low-density materials such as hemp, wood shavings, bark particles, sugar cane, cotton waste, and pulp-mill waste have been used.
Chlorides, silicates, nitrates, and sulfates have been added to Portland cement to increase the binding of the particles in the concrete. Various additives are shown in U.S. Pat. No. 1,309,296 to Marks (1919), U.S. Pat. No. 1,463,123 to McAllister (1922), U.S. Pat. No. 1,484,370 to Bartlett (1924), U.S. Pat. No. 2,057,330 to Eichert (1936), U.S. Pat. No. 2,592,345 to Schnell and Bosshard (1947), U.S. Pat. No. 3,264,123 to Coming and McNally (1962), U.S. Pat. No. 3,311,483 to Gamier et al. (1967), and U.S. Pat. No. 5,122,405 to Sanchez (1992).
It is often desirable to utilize cements and concretes which are lightweight, strong, durable and affordable. It is known that many of the techniques for making lightweight organic materials require the process of using hammer mills, presses, heat, extended curing time, bringing the slurry to boiling point, and slaking the material in vats for days. U.S. Pat. No. 5,112,405 to Sanchez (1992), discloses the use of ammonium sterate to produce gaseous bubbles by reacting a calcium chloride. His claim was that the bubbles by reacting to calcium chloride produced a lighter, better-insulated board. What is needed is a less expensive and more efficient way of creating the bubbles.
Lightweight cement designs usually have higher than normal water demands, resulting in slow setup times, and weak, highly porous cement. When sawdust, rubber crumbs, and similar lightweight fillers have been used in the mix, the cement tends to encapsulate rather than bond to the filler. What is needed is a tighter pore system that would not allow the aggression of the elements to penetrate, would have high insulating qualities, and would bond to the fillers used.
Another aspect of using lightweight cements other than for building purposes is well known. Lightweight cement is also used in the containment of liquid contaminants. In dealing with underground cylinders and tanks, what is needed is a material with the capacity to absorb the contaminants and further to encapsulate said contaminants to reduce the possibility of leaching of the contaminants. If the contaminants are not totally contained, there are possibilities that the dangerous liquids could leach into the surrounding water table and pollute drinking water and surrounding soil.
Mechanical and electrical vibrators are often required in the process of filling cylinders and tanks. Due to the unpredictable nature of many contaminants, mechanical and electrical vibrators prove to be dangerous. It is desirable to have a material that does not require the use of mechanical and electrical vibrators or other devices that could prompt an explosion. Materials that are easy to pour, easy to clean up and affordable to use are desirable and needed for these purposes.
In the past, bentonite has been used as a primary component in a grouting composition for sealing a borehole, U.S. Pat. Nos. 4,964,918 and 5,021,094 to Brown et al. (1990 and 1991), as a cementitious mud for constructing a water impermeable wall in the ground, U.S. Pat. No. 3,759,044 to Caron et al. (1973) as a high solid slurry, U.S. Pat. No. 5,266,538 to Knudson et al. (1993) and as an additive for concrete block, U.S. Pat. Nos. 4,568,390 and 4,673,437 to Gelbman (1986 and 1987) and U.S. Pat. No. 4,861,378 to Watanabe et al. (1989). Although the ability of bentonite to reject water is well known, it has not been used to insure the bonding of a cementitious mixture to a noncementitious filler.